Computation Exactness Exploration of Exact Quantum Adders in NISQ

With the rise of Noisy Intermediate-Scale Quantum (NISQ) computing, the selection of suitable adders becomes more crucial for optimizing quantum computations. The ripple carry adder (RCA) and carry lookahead adder (CLA) are fundamental quantum adder architectures, yet, their performance under NISQ environments remains to be largely unexplored. In this paper, we extensively compare the RCA and CLA designs through a systematic analysis in NISQ computing. Our results reveal that the proposed quantum RCA has a 29.7% lower error rate than the existing quantum CLA, highlighting the importance of simple exact quantum adder designs tailored for specific noisy quantum hardware constraints. These findings offer the crucial insights for designing efficient quantum algorithms and optimizing quantum circuits for practical NISQ systems.